Compressor air seal



Feb. 14, 1967 J. J. WELCH ET AL 3,303,997

COMPRESSOR AIR SEAL Filed April 21, 1965 United States Patent O 3,303,997 COMPRESSOR AIR SEAL Joseph J. Welch, Thompsonville, and John D. Rosenthal, West Hartford, Conn., assiguors to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Filed Apr. 21, 1965, Ser. No. 449,738 5 Claims. (Cl. 230-132) This invention relates to a `sealing arrangement for relatively rotating elements and has particular utility at the delivery end of an axial flow compressor.

One feature of the invention is the effective sealing between the rotor and stator to minimize leakage and dur-ing lall rotational speeds. Another feature is to maintain a sele-cted but limited flow of air from the compressor past the seals in spite of the growth of the rotor during operation either from centrifugal loading or iby thermal expansion.

One feature of the invention is the sealing at the high pressure end of a multistage compressor to provide a limited and controlled flow of air under pressure for cooling the last rotor stage and also to supply a limited and controlled flow of high pressure air past the seals at this point which may be used, for example, for cooling purposes since this air, although heated by compression, is still much cooler than the turbine gas.

Other features and advantages will be apparent from the specification and claims, and from the accompanying drawing which illustrates an embodiment of the invention.

The single gure is a longitudinal sectional view through the last stage of an axial flow -compressor showing lthe invention.

In the arrangement shown the compressor casing 2 is made up of two parts bolted together, yone part 2a constituting the outer case for the successive compressor stages and the -other part 2b constituting the outer Wall of the diffuser 4, the latter also supporting a row of vanes 6 downstream of the last row yof rotor blades 8.

The rotor blades 8 are supported by a rotor disc 10 and directly upstream of the rotor bla-des is a row of cornpressor vanes 12 supported at their outer ends by a shroud 14 positioned within the casing 2a and supporting at their inner ends an inner shroud 16 connected as by a disc 18 to a sealing ring 20. This type of construction is generally old and well known in the Savin Patent No. 2,747,367.

The diffuser 4 has an inner Wall 22 and the two walls are held in spaced relation to each other by a plural-ity of vanes 24 extending between the walls. One or more of the vanes 24 has a forwardly positioned opening 26 substantially midway of the vanes to draw off air from the diffuser and discharge it through an opening .28 in the inner wall 22 into the chamber 30. This chamber is defined by an elongated sealing sleeve 32 forming the inner wall of the chamber, a radial flange 34 at one side of the opening 28 and extending inwardly to engage the sleeve 32 and another flange 36 at the other side of the opening 28. This latter flange supports the sleeve 32, as shown.

The rotor disc has radially spaced Iinner and outer centrifugal flanges 38 and 40 on one lateral surface thereof, these flanges being concentric to each other and in a position to receive the free end of the sleeve 32 therebetween. The sleeve has inner sealing flanges 42 projecting radially inward from the sleeve with the peripheries thereof closely spaced from the flange 38 and outer sealing flanges 44 which exten-d radially outward from the sleeve 32 into close proximity to the flange 40 on the rotor. These sealing flanges are so arranged that there is a metering gap 46 provided between the tips of the flanges 44 and the rotor flange 40 and another metering gap 48 between the tips of the sealing flange 42 and the rotor flange 38. The gaps 46 and 48 constitute a metering device which adjusts to engine conditions because of radial disc growth either as a result of the centrifugal loads thereon or the thermal expansion thereof and also the radial thermal expansion of the sealing flanges 42 land 44. During certain periods of engine operation metering at 46 is dominant and the flow past this metering gap determines the amount of sealing air passing around the end of the sleeve 32. Under certain conditions at substantial or maximum growth of the rotor the gap 46 becomes larger an-d the gap 48 becomes smaller so that the gap 48 effectively provides the desired metering. Air passing around through these gaps is supplied rfrom the chamber 30 through openings 48 in the flange 34 and the air having passed through these gaps may be used for any desired sealing or cooling purpose within the engine. It will be understood that this pressure of air being taken from a point directly downstream of the compressor is withdrawn from the point of highest pressure within the engine and being `withdrawn from the center of the air flow is cooler than the air flowing adjacent to either Iwall 2b or 22. Also, although the air at this point is quite warm from having compressed within the compressor, it is still substantially cooler than the gas within the turbine and may effectively be used' for cooling parts of the turbine.

The inner wall 22 of the diffuser supports the inner shroud 50 of the row of vanes 6 so that this shroud constitutes in effect an extension of the diffuser wall. This wall thus supports a sealing ring 52 having radially, inwardly-extending sealing flanges 54, the inner peripheries of which are located at closely spaced relation to the outer surface of the rotor flange 40. These flanges provide a gap 56 between through which a measured amount of air from the chamber'30 may flow to re-enter the gas path at a point between the inner ends of the rotor blades 8 yand the adjacent vane shroud 50.

It is to be understood that the invention is not limited to the specific embodiment herein illustrated and described, but may be used in other ways Without departure from its spirit as defined by the following claims.

We claim:

1. A sealing and metering device for a compressor including a rotor having a row of blades thereon, a stator having a row of vanes thereon cooperating with the blades, and defining an annular duct for air through the compressor, said rotor having inner and outer radially spaced axially extending flanges thereon, and sai-d stator having a cooperating axially extending ring located between said flanges, said ring having peripheral sealing flanges on its inner and outer surface extending substantially into engagement with the inner and outer flanges respectively on the rotor, and means for removal of air from substantially the midpoint radially of the duct for metering past said sealing flange.

2. A seal construction including a rotor member having a row of blades thereon and a stator having a row of vanes thereon cooperating with the blades an-d defining an Iannular duct for air through the compressor, one of said members having a pair of spaced axially extending inner and outer flanges thereon in concentric relation, the lateral surfaces of these flanges exposed to the working fluid being parallel to one another, `and the other of said members having a substantially cylindrical element projecting therefrom between said axially extending flanges, said element having a plurality of radially extending sealing flanges on opposite sides'thereof extending into closely spaced relation to the peripheral surfaces, the axially extending flanges thereby providing metering gaps between the sealing flanges .and the lcooperating inner and outer flanges, such that when a growth occurs in the rotor one set Iof metering gaps will decrease in dimension as the ice' other set increases, and means for withdrawing air from the duct for metering past said sealing flange.

3. A seal construction as in claim 2 in which the metering gaps between the outer ange and the sealing flanges are in series relation t-o the other metering gaps Vwith respect to the ow of fluid therethrough.

4. A seal construction as in claim 2 in which said other of said members also has a second sealing element outside said outer flange, said element having sealing anges cooperating with the outer surface of the outer ange on the rotor.

5. A sealing and metering device for a compressor including a rotor having a row of blades thereon, a stator having a row of vanes thereon cooperating with the bla-des, and defining an annular duct for air through the compressor, said rotor having inner and outer radiallyspaced axially extending flanges thereon, and said stator having a cooperating axially extending ring located between said anges, said ring having peripheral sealing flanges on its inner and outer -surface extending substantially into engagement with the inner and outer flanges respectively on the rotor, means for withdrawing 'air from the duct for metering past sai-d sealing flanges, and said axially 4 extending ring being relatively long axially and being secured to the stator at a point axially beyond the air withdrawing means to form'a chamber through which the air is directed from the withdrawing means to the sealing flange.

References Cited by the Examiner l UNITED STATES PATENTS 1,978,239 10/ 1934 Wheeler 277-55 2,084,909 6/ 1937 Hoimann 277-55 2,647,684 8/1953 Lombard 103-11'1 2,682,363 6/1954 Lombard et al. 230-133 2,722,101 11/ 1955 Wosika 253-77 .3 2,937,495 5/1960 YPerry 230-116 3,189,320 6/1965 Beldecos etal 253-67 3,250,512 5/1966 Petrie 253-69 FOREIGN PATENTS 1,262,633 4/ 1961 France.

DONLEY I. STOCKING, Primary Examiner.

HENRY F. RADUAZO, Examiner. 

1. A SEALING AND METERING DEVICE FOR A COMPRESSOR INCLUDING A ROTOR HAVING A ROW OF BLADES THEREON, A STATOR HAVING A ROW OF VANES THEREON COOPERATING WITH THE BLADES, AND DEFINING AN ANNULAR DUCT FOR AIR THROUGH THE COMPRESSOR, SAID ROTOR HAVING INNER AND OUTER RADIALLY SPACED AXIALLY EXTENDING FLANGES THEREON, AND SAID STATOR HAVING A COOPERATING AXIALLY EXTENDING RING LOCATED BETWEEN SAID FLANGES, SAID RING HAVING PERIPHERAL SEALING FLANGES ON ITS INNER AND OUTER SURFACE EXTENDING SUBSTANTIALLY INTO ENGAGEMENT WITH THE INNER AND OUTER FLANGES RESPECTIVELY ON THE ROTOR, AND MEANS FOR REMOVAL OF AIR FROM SUBSTANTIALLY THE MIDPOINT RADIALLY OF THE DUCT FOR METERING PAST SAID SEALING FLANGE. 